The present invention relates to a semiconductor device and a manufacturing method thereof. More particularly, it relates to a semiconductor device in which recesses are formed in the main surface of a semiconductor substrate, and a manufacturing method thereof.
A semiconductor device in which recesses are formed in the main surface of a semiconductor substrate is disclosed in, for example, Japanese Unexamined Patent Publication No. Hei 7(1995)-131009. In the semiconductor device of the publication, in the channel region of a MOS (Metal Oxide Semiconductor) transistor, a fine trench (recess) is formed orthogonal to the channel width direction. Accordingly, the effective channel width can be made longer than the actual gate dimension. As a result, it is possible to obtain a MOS transistor miniaturized in the channel width direction to the maximum with the stable operation characteristic being kept. This is described in this publication.